Heretofore, there is a card type electronic device referred to as a PC card, and there is realized a device equipped with various types of functions for expanding a function of a portable personal computer or the like. Examples of the device include a communication card and a memory card for a modem, an LAN, a radio telephone and the like. There is also a card type electronic device referred to as a CF (Compact Flash®) card, and there is realized a device equipped with various types of functions in the same manner as in the PC card. Since this CF card has a shape which is smaller than that of the PC card, the card is used in a small-sized unit such as a portable telephone or a portable terminal in the form of a PDA or the like.
Moreover, assigning of a signal to an external terminal of the CF card conforms to a PC card standard. When an exclusive-use or dedicated adapter is used, the CF card can be attached to a PC card slot of the portable personal computer or the like, and used as the PC card (see, e.g., Patent Document 1). The exclusive-use adapter has a simple constitution in which a wiring line is simply extended to adapt the shape of the card to that of the PC card, and any control circuit is not disposed.
[Patent Document 1] Japanese Patent Application Laid-Open No. 2000-194800
Each of the above CF and PC cards operates on receiving a current supply from the card slot of a host device to which the card is to be attached. Moreover, the CF card differs from the PC card in a standard value of a maximum current supplied from the card slot in the standard, and the standard value of the maximum supply current of the CF card slot is smaller. Therefore, in consideration of a case where only the CF card is attached to the CF card slot and used, a function or a performance realized by the CF card is sometimes designed so as to be more restrictive than that realized by the PC card.
For example, in a radio telephone standard of a code division multiple access (CDMA) system, a plurality of classes are defined in transmission outputs from the terminal. However, even in a case where the PC card can cope with the class of a certain maximum transmission output, when the class of the maximum transmission output is implemented by the CF card, a maximum consumption current sometimes exceeds the maximum supply current standard value of the CF card slot. Therefore, the CF card has to be designed so that the card does not cope with the class of the maximum transmission output.
For such a reason, the above conventional combination of the CF card and the exclusive-use adapter can be used as the PC card, but the function or the performance equivalent to that of the PC card is not realized in some case. This results in a situation in which a user prepares the CF card for the portable device, and prepares the PC card in respect of the function or the performance, and a burden imposed on the user is large.